1. Field of the Invention
The invention relates in general to a voltage regulating method, and more particularly to a voltage regulating method for regulating a word line voltage in a memory.
2. Description of the Related Art
In the modern age, in which the technology changes with each passing day, non-volatile memories, such as flash memories, are widely used in various electronic products. Conventionally, the threshold voltage of the flash memory cell and the data stored therein are determined by controlling the number of electrons trapped by a floating gate or a nitride layer of the memory cell.
FIG. 1 (Prior Art) is a distribution graph showing a threshold voltage of a memory cell in a conventional flash memory. As shown in FIG. 1, for example, the memory cells of the flash memory may be substantially divided into group distributions G_0 and G_1. Each memory cell in the group distribution G_1 has the higher threshold voltage, and correspondingly stores the data value of 0, for example. Each memory cell in the group distribution G_1 has the lower threshold voltage and correspondingly stores the data value of 0, for example. The corresponding lowest threshold voltage in the group distribution G_1 has the voltage level BV0, for example, and the corresponding highest threshold voltage in the group distribution G_0 has the voltage level BV1, for example.
In the modern technology, the word line voltage having the level ranging between the voltages BV0 and BV1 is provided to drive the to-be-read memory cell in the flash memory. The voltage difference between the voltages BV0 and BV1 is defined as a sensing window, for example.
However, the size of the sensing window is correspondingly reduced with the update of the technology of the flash memory. Thus, it is an important direction in the industry to design a method capable of effectively regulating a level of a word line voltage.